AERODESIGN - Preliminary Design Methodologies

Executive Summary:

The AERODESIGN project provides a design tool for the analysis and optimization of preliminary aircraft configurations. The overall tool design is based on a multi-segment and multi-level modular framework that divides the preliminary design methodology scope into eight different modules: geometrical, aerodynamic, engine data, weight and balance, mission and low speed performance, costs analysis, emissions and noise analysis. In an integrated process of design optimization, these modules are integrated by various technologies into a cost-effective solution. The tool performs aircraft design optimization based on changing the shape of its lifting surfaces, which are provided to the tool as input. The software tool was developed in a modular fashion so as to easily adjust, update, modify or enhance any of the modules individually, whilst the end result is strictly an application. The AERODESIGN tool is stand-alone, although it requires the availability of external resources (applications) to work properly. It includes a Human Machine Interface (HMI) that allows the user to operate the tool and obtain feedback information on the design results.

Project Context and Objectives:

To study the future configuration of commercial aircrafts, it is important to have the most efficient method of preliminary design supported by the most complete database with information on existing assets and validated results. The initial conceptual and preliminary design phase drives most of the cost of the airplane project and lifecycle costs. Incorporating cost models in the early design enables the realization of even further cost reduction measures and trade-offs at the preliminary design level. Adequate design support tools are required in the early design process to handle in the most efficient way the largest amount of multidisciplinary variables, making sure the best concept is selected as a starting point to the detailed design phase.

The overall tool design is based on a multi-segment and multi-level technical framework. The AERODESIGN project has developed and validated a design tool capable of performing a preliminary design and analysis of an aircraft in the preliminary design phase, and enable achieving the pollution and noise reduction targets for the regional aircraft entering the market in the coming decades. To perform the analysis the following modules were implemented:

Initiator (INIT) – is a general statistical module that is used to obtain a general aircraft architecture starting from the aircraft requirements and a large database of reference aircraft. The general aircraft architecture defines an initial aircraft configuration solution that is the base for the Multi-Model Generator module.

Multi-Model Generator (MMG) – Execute all the required computations for deriving all the geometrical parameters necessary for the subsequent analysis and weight and balance computations. It is divided into two components: Geometry Module and Weight and Balance module.

The Geometry module (GEOM) takes the general aircraft architecture generated by the statistical pre-sizing, determine the layout of the aircraft including cabin configuration, output a CAD geometry file for visualization and output structured information suitable for subsequent analyses

The layout evaluates in detail the following parameters:

Fuselage: lengths and cross sections of cockpit, cabin, tail cone, floors, cargo holds, doors and emergency exists

Wing: size and positioning of the ailerons, internal fuel volume

Tails: size of horizontal tail and elevator, size of vertical tail and rudder

Engine: positioning and size

The information produced by the Geometry module comprises:

• a pdf file describing 2D views of aircraft
• a CAD geometry file in IGES format, which is directly readable by a CAD software such as CATIA
• airfoil positions, coordinates
• fuselage cross section shape and coordinates

The Weight and Balance module (W&B) determines a detailed weight breakdown of the aircraft and determine the centre of gravity of the aircraft during loading/unloading of passengers and during flight when fuel is burned.

Aerodynamic module (AERO) –determines the aerodynamic loads and moments acting on the aircraft. The aerodynamic analysis performed by the Aerodynamic module includes a 3D subsonic potential analyses (vortex lattice method), viscous drag evaluation through a semi-empirical approach based on wetted areas and drag build-up methods and aerodynamic lift contribution due to control surfaces deployment

The Aerodynamic module is also able to output at request, for a given aircraft geometry and flow condition: Aerodynamic lift, drag (total drag and its terms: induced and viscous) and pitching moment, Polar for the entire aircraft, Initial stall position on wing, Stability derivatives and Estimated Buffet Limits (CL vs Mach number).

Engine Data Module (ENG) – provides fuel consumption and thrust for each flight phase/engine ratings.

This module also has the capability to evaluate the variation of weight and main dimensions against thrust scaling factor as well as provide information regarding jet velocity, weight dimensions and engine sizing rating.

Mission and Low Speed Performance Module (PERF) – This module will calculate aircraft performance at different flight segments, such as: take off, climb, cruise, acceleration and deceleration Phases, descent and landing

Single Performance Points will be also calculated namely, Emergency Take off & Landing Performance; All engines and one engine out ceilings; acoustic take-off and approach path; sustained turn rate Maximum speed; Specific Range vs. Speed Curves

Costs Module (COSTS) is responsible for the calculation of Direct Operating Costs as well as Recurring production costs

Engine Emissions Module (EMISSIONS) is the module responsible for the calculation of engine emissions for a specific trajectory in various flight phases

Noise Module (NOISE) – The NOISE Module is responsible for the calculation of internal and external noise levels, including noise iso-level curves around the airport.

Optimization module (OPT) performs optimization of the lifting surfaces, through the optimization of a set of design variables (parameters) that define the form of the lifting surfaces. The optimization shall find an aircraft design that achieves one of the following (user selected) goals: MTOW, Cost, Noise or Emissions.

The Optimization module implements a gradient based method, starting from an initial design point (an initial aircraft configuration) and shall be restricted to small changes in the design variables.

Reporting Module (REP) – The Reporting Module is responsible for presenting the analysis and optimization information on a tabular or graphical mode. This output will report the following information: Geometry of Aircraft and Engine; Characteristic weights; Weight Breakdown; Aerodynamic Data; Mission Results; Engine thrust in design points; Noise levels and footprints and Engine Emissions.

Project Results:

The AERODESIGN project has achieved all the Scientific & Technological target objectives established at begin of the activities. All the Validation and validation activities were developed and reported in the WP5 (Integration and Verification).

As main results, based on the test and validation activities, we can state that AERODESIGN is a powerful tool able to assist on the analysis and optimization of preliminary aircraft configurations.

Potential Impact:

The AERODESIGN Consortium has developed several dissemination activities under the scope of the WP7 (Dissemination and Exploitation). The main objectives of such activities were to ensure a systematic dissemination of the project outcomes among the aeronautical community (public dissemination) and to facilitate the collaboration and information exchange between partners (internal dissemination).

The dissemination activities were under the responsibility of each consortium member and therefore, each partner reports on the activities they carried out for the dissemination of the AERODESIGN project results, activities that are compatible with the any protection of intellectual property rights, confidentiality obligations and legitimate interests of the owner(s) of the foreground.